REVIEW: G-Force 700N Clutch Block Kit with Engine Mounts

G-Force Technologies has been the leader in bringing out high quality and high performance products for the heli market. Here at RC Heli Resource we have reviewed a number of great offerings from G-Force so when we got the opportunity to review the new adjustable clutch block and motor mounts for the T-Rex 700N we were more than happy to oblige. Read on to see the full review.

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The T-Rex 700N is equipped with a plastic clutch block that has no adjustment and while simple in design, this setup yields a few disadvantages.

Over time worn main gears can develop enough play or backlash that gear slippage and stripping can occur.
Over time the plastic bearing blocks can expand due to heat and the excessive stresses that occur from 3D flight and bearing slippage can occur.
Align has proven themselves more than capable with their design tolerences, however, it is possible to get a kit with excessive backlash right out of the box.

G-Force has taken these factors into account and developed this adjustable clutch block and motor mount kit which allows for infinite adjustments to obtain a perfect meshing between the clutch pinion and main gear. Whether trying different gear ratios, tightening up the mesh on a worn main gear, or obtaining that perfect mesh right out of the box the G-Force Clutch Block Kit will help you accomplish these tasks.

G-Force T-Rex 700N Clutch Block Features:
-Triple radial bearings (factory installed)
-Slotted adjustment holes (uses standard M3 locking nuts)
-Allows use of stock pinion clutch nut (no pinion shifting)
-Adjustable engine mounts included the kit (bonus)
-Anodized (for good looks and durability)

Quality - Score 10:

The quality of these parts are second to none. The machined aluminum looks superb and the parts just have the look that says precision.

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Instructions – 9.0:

The installation instructions are contained on one single sheet of paper. They are very simple but give you all of the information you need to complete this installation.

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Installation – 9.0:

There are basically two main components of the installation of this kit. The installation of the adjustable clutch block assembly and the installation of the adjustable motor mounts. The clutch block unit comes with new pinion shaft bearings and starter shaft bearing pre-assembled so this makes things easier. However, in order to complete the installation of this kit you have to remove the old clutch block and motor mounts. This requires that you remove the skids, bottom plate, muffler from engine, engine and finally the clutch block assembly.

Note: When removing the stock clutch block and the engine, care must be taken to not strip the M3 shoulder socket cap bolts. I recommend using a monokote heat gun to heat the bolts before removal. If you strip one of these bolts you can use a small cut-off blade and dremel tool to cut a flat in the head of the bolt and use a screw driver to remove them.

Once you have removed the stock clutch block assembly, you must remove the starter shaft by removing the hex start coupler and sliding it out of the assembly and remove the two bearings above the pinion gear by separating the plastic block halves and removing the clutch nut. This enables you to slide the bearings off of the pinion shaft.

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Then you will remove the starter shaft guide from the G-force unit and slide the stock pinion gear/clutch bell assembly through the bearings of the new clutch block and secure it with the stock clutch nut and blue thread locker. Then you can re-install the starter shaft guide and install the starter shaft and secure the hex start coupler. Now the G-force Adjustable Clutch Block is ready to be installed into the frames.

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The installation of this assembly is easier than the stock assembly because the G-Force unit does not have the keyed area like the plastic unit so the frames do not have to be separated for it to fit in. It just slides right into place. This assembly is secured in place with the four (4) stock M3 x 10mm shoulder socket cap bolts that are used in the stock block, however, the installation instructions call to purchase new ones and you can purchase a package of 16 of these under Align Part No. HN6015. The new bolts are needed since these bolts will be threading into locknuts and the instructions note NOT to use bolts with left over lock tight residue.

There are threaded holes in the block where the keyed slots in the frames are and the kit supplies two (2) M3 x 6mm bolts with washers to thread into these holes in order to aid in tightening the block during adjustment. For adjustment, you tighten all of the shoulder socket cap screws into the locknuts and back off about a quarter of a turn. This allows the assembly to slide back and forth for proper meshing. On my machine, I used a small strip of paper (See the picture below) to thread in between the pinion and main gear and then using my hands pulled the assembly toward the main gear being careful to make sure that the pinion was square to the main gear. I then tightened the M3 x 6mm socket cap bolts and checked the mesh. After a few tries, I had obtained a mesh that I liked. The M3 x 6mm bolts secure the block while the remaining four (4)shoulder socket cap screws are tightened into the locknuts. You can leave these bolts in place after tightening all the bolts for additional securement or you can remove them after the four (4) shoulder socket cap screws are secure. The clutch assembly installation is now complete and we go on to the motor mounts.

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The new adjustable motor mounts need to be installed into the frames first before installing the engine. Using the new shoulder socket cap bolts along with the supplied locknuts secure the mounts into place by fully tightening the bolts and then like before loosen these bolts about a quarter turn so the mounts can move for adjustment. Now you can install the engine.

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Once you install the engine securely to the motor mounts you should be able to slide the engine back and forth. If you slide it to one extreme you will be able to feel binding when you rotate the main gear and same for sliding it in the other extreme. Somewhere in between the points you should be able to find a location where you feel no binding. You then can tighten up the motor mounts to the frames and check again to make sure there is no binding. At this point in the installation, I realized there was an issue. The width of the engine block would not allow the engine to slide into the frames far enough to be aligned properly. At this point, I decided all that was needed was for me to file a little off of the engine crankcase mounts. You can see from the pictures below where the engine crankcase mounts were to wide and how they looked after a filed them. This was a simple fix but if you do this be very careful to tape up all the openings of the engine to ensure no metal shavings can enter the engine.

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I feel that in many cases this issue would not be present and there would not be the need for filing the motor mounts like I had to. In my case, I am installing this kit into a well used machine with the original stock main gear and the clutch block needed to be adjusted towards the main shaft a few millimeters. If you are using the larger Mod 1 gears this may not even be an issue. Nevertheless, it was a simple fix.

I received a tip from Garf at G-Force after completing this review that an easy solution should the need arise to move the engine inwards into the frames would be to file off the excess CF from the frames instead of filing the engine block. I agree with this solution as it would have been easier to complete and then there is no chance of harming an engine. G-Force has added this tip to there Installation Instructions. Thanks Garf.

At this point, everything is secure and you can re-install the muffler. Next you will re-install the bottom plate and skids and depending on your adjustment there may be the need to widen or slot the holes in the bottom plate in order to secure the supplied M3 x 8mm socket head bolts and washers to the bottom of the engine mounts. This can be done easily with a dremel or file. (See picture below)

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Make sure everything is secure and tightened. Remember to reconnect all of your fuel lines, ect. and you should be ready to go flying.

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Overall – 9.5:

Overall, I found the quality exceptional and the build very straightforward. The installation does require removal of a few components and some attention to detail during assembly to make certain everything is adjusted correctly. It is a definite aid in removal of any slop or unwanted backlash in the gear train of the T-Rex 700. For those of us who are willing to sacrifice a little simplicity to have a little more control over our machines this kit is right up your alley.

For more information and to purchase this kit and any other G-Force product please visit the G-Force Technologies website.